The present invention pertains generally to methods and apparatus for tipping smoking articles, and pertains more especially to such methods and apparatus for tipping oval smoking articles.
In the manufacture of smoking articles, particularly cigarettes, it is conventional to make a continuous tobacco rod (a paper tube filled with shredded tobacco or tobacco substitute) and to cut the continuous rod to the length of individual cigarettes. A continuous rod of filter material is extruded and cut into lengths. The resulting filter plugs are collected in trays and placed in the hopper of a tipping machine, which cuts the filter plugs to twice the length of a single filter, joins each double-length filter plug to two filterless cigarettes, and severs the resulting assembly to form two complete cigarettes.
The filter plugs are gravity-fed from the hopper into flutes or grooves in the periphery of a rotating drum. The filter plugs are held in place in the flutes by means of vacuum suction exerted from the drum interior. The filter plugs can be passed from one such drum to another by proper timing of the rotations of the two drums, and by simultaneously deactivating the suction applied to a particular groove of the first drum as that groove comes face-to-face with a groove of the second drum. This permits a filter plug in the first flute to be pulled over into the opposing flute of the second drum by the suction applied to the latter. The filter plugs passed in this manner from one drum to another eventually are transferred to the flutes of a feed drum. In each flute two previously-deposited cigarette rods flank the filter plug end-to-end.
A web of cork or other tipping material is drawn from a roll thereof and has glue applied to one side. The web is cut off in lengths by cork knives, and one edge of each length is applied to a filter-plug-and-cigarette assembly in such a manner as to extend over the entire length of the filter plug and to overlie a small portion of each cigarette rod, the adhesive on the tipping material sticking to the plug and the rod.
The resulting double cigarette assembly is transferred to a rolling drum, beside which is a metallic rolling block. Each cigarette assembly is rolled along the rolling block by the drum. The rolling action wraps the tipping material around the cigarette assembly, to which it adheres as a result of the glue. Suitable heating elements in the rolling block commonly are used to cure the adhesive rapidly.
The double cigarette assembly is then transferred to a cutter drum, which moves the assembly past a disc knife that severs it into two complete cigarettes. The cigarettes are then inspected and moved to a discharge point, from which they are taken to another machine for packing.
The conventional tipping machine described above is designed to handle cigarettes of circular cross section. It would be desirable to be able to adapt a standard cigarette tipping machine for use in the rapid, economical large-scale manufacture of cigarettes having an oval cross section, which have hitherto largely been a luxury product requiring special equipment for virtually every stage of their manufacture. Various problems arise in making such an adaptation.
For example, it is difficult to transfer oval filter plugs from the hopper to a drum of the conventional type in such a manner that every flute will contain a filter plug and so that each filter plug will have the same predetermined orientation about its longitudinal axis (hereinafter, "angular orientation"). In addition, it has been found to be impossible, as a practical matter, to wrap tipping material around a cigarette assembly having an oval cross section, using standard tipping machine equipment. Related copending applications Ser. No. 480,809, filed Mar. 31, 1983, now U.S. Pat. No. 4,535,790, entitled "Method and Apparatus for Aligning Oval Cigarette Filters," and Ser. No. 584,366, filed Feb. 28, 1984, entitled "Method and Apparatus for Tipping Smoking Articles," both assigned in common herewith, are directed to solutions of these problems.
Another problem arises when it is desired to use a standard tipping machine to wrap tipping material around an oval cigarette assembly having a circumference smaller than the circumference of a standard cigarette. The rolling drum of a standard tipping machine has a particular diameter and a particular number of flutes spaced evenly about its circumference for transferring cigarette assemblies on and off the drum. Each cigarette assembly rolls back two flutes along the drum circumference as tipping material is rolled around it.
The arc length along the drum circumference between flutes is not critical when rolling a circular cigarette, because the rolling distance, two flutes, for different circumference cigarettes is fixed. The number of revolutions necessary for rolling any given circumference circular cigarette two flutes can be controlled by varying the length of the rolling block. On one standard cigarette making machine, the distance between flutes is one-and-one-half times the circumference of a standard cigarette, so that a standard cigarette makes one-and-one-half revolutions as it rolls from flute to flute. If a circular cigarette having a smaller circumference is rolled on the machine, it will roll a greater number of times but, because it is circular, its angular orientation when it reaches the second and third flutes will be indistinguishable from that of a circular cigarette of any other circumference.
However, when tipping oval or other non-circular cigarettes, it is desirable to have all cigarettes in a particular angular orientation on the various drums (except while they are actually being rolled), especially at the transfer points between drums. One preferred orientation for an oval cigarette is that in which the major axis of the cross section of the cigarette is parallel to a line tangent to the drum surface at the point of contact between the drum and the cigarette.
If a cigarette has the circumference of a standard cigarette for which the machine was designed, it will make one-and-one-half revolutions as it rolls between flutes, even if it is oval. Assuming that it starts at the preferred angular orientation, it will finish at that orientation. However, if an oval cigarette has a circumference smaller than the standard circumference and it starts at the preferred angular orientation, it will finish at an angular orientation other than that which is desired.
This problem can be solved by making the rolling drum smaller to decrease the distance between the flutes while maintaining the same number of flutes, or by adding flutes to the drum. However, implementing either of these alternatives would require changing the size, location, and/or speed of rotation of some or all of the other drums in the machine. Further, additional flutes can only be added to the drum without changing its size in those cases where the ratio of the desired circumference to the standard circumference is equal to the ratio of the standard number of flutes to the desired number of flutes, so that the flutes can be spaced evenly about the drum.
It is therefore the principal object of the invention to provide a method and apparatus for applying tipping material to a filter plug and tobacco rod of oval cross section and wrapping the tipping material therearound, while rolling the cigarette assembly a predetermined number of times to maintain a desired angular orientation, regardless of the circumference of the cigarette.
Another object of the invention is to achieve the foregoing objects in a manner which permits the ready and easy adaptation of existing tipping machines to the production of oval cigarettes of non-standard circumference.